The principle and application fields of pressure sensors

The principle and application fields of pressure sensors

A sensor is a device that converts various non electrical quantities (including physical quantities, chemical quantities, biomass, etc.) into another physical quantity (usually electrical quantity) that is convenient for processing and transmission according to a certain pattern. Sensors are generally composed of three parts: sensitive components, conversion components, and measurement circuits, sometimes requiring an additional auxiliary power supply. The sensor is shown in the following block diagram.

Block diagram:

　

　 　 　 　 　
Manufacturing semiconductorsPressure sensorThe basic principle is to utilize the piezoresistive effect of silicon crystals. After being subjected to stress, the resistivity of monocrystalline silicon materials undergoes a significant change, which is called the piezoresistive effect.

The component materials used in pressure sensors are monocrystalline silicon, diffusion doped silicon, and polycrystalline silicon with piezoresistive effects. According to the fact that when a crystal is not subjected to directional stress, its conductivity is isotropic, and only when subjected to directional stress does it exhibit anisotropy. Stress can cause changes in energy bands, energy valleys, and electrical resistivity, resulting in a change in resistance, resulting in a piezoresistive effect. The monocrystalline silicon effect includes n-type and p-type silicon piezoresistive effects. The purpose of selecting diffused silicon is to select appropriate diffusion conditions based on the piezoresistive characteristics of the silicon diffusion layer at different temperatures when designing and manufacturing pressure sensors, striving to ensure good performance of the pressure sensor. Polycrystalline silicon has a wide range of applications in sensors, as a microstructure, filling material, and sensitive material.

The classification of pressure sensors by purpose mainly includes pressure monitoring, pressure measurement, pressure control, and measurement converted into other quantities. According to the power supply method, it is divided into piezoresistive sensors and piezoelectric sensors. The former is passively powered and requires an external power supply. The latter is a type of pressure sensor that generates charges on its own and does not require an external power source. It can be classified into low precision and high precision pressure sensors based on the different accuracy of pressure measurement in different fields.